When Diablo 4's Season of Blood launches on October 17th, all Renown points and rewards that were previously earned by other characters will apply to all current and future characters on the same account. This means that players will no longer need to grind Renown ever again, once the rewards associated with that Renown have been earned.
This is a massive quality-of-life improvement, as many players in the community have voiced their displeasure at the thought of having to farm Renown every Season in Diablo 4. Season of Blood releases on October 17th, and will also include a new Seasonal Questline, 5 new Endgame Bosses, and more opportunities for players to target-farm Uber Uniques!
Diablo 4 Season of Blood Announcement Diablo 4 Season 2 Official Blog Post